Yes, some people here have bought it directly at the store. Gotta remember, the Mixamp was hard to get for a while, and just came back in stock on Astro's site. Not sure how that affects Best Buy's stock.

I measured my head yesterday and apparently we have a similar head size. Roughly 45.5 cm. Is the he-400 comfortable around your head?

Let me know how the mixamp+magni+he-400 combo works. I might be mistaken but the sound coming off the mixamp is just amplified when it goes from the mixamp through 3.5mm to rca cables > magni and then the headphones. It is not distorted or otherwise altered.

Yes, you're using the Mixamp as a pre-amp, so the signal is amplified by the Mixamp and then amplified by the Magni. Not completely ideal, but the only way to get a good, amped Dolby Headphone signal for your headphones. Trust me, it's considerably better to amp after the Mixamp than using the Mixamp alone.